(1) Field of the Invention
The present invention relates to a composite phylosilicate and a process for the preparation thereof. More particularly, the present invention relates to a composite phylosilicate which has a large specific surface area and a large pore volume, shows an excellent adsorbing property to various substances and is valuable as an adsorbent or the like.
(2) Description of the Related Art
A phylosilicate generally has, as a basic skeleton, a two-layer or three-layer structure comprising a tetrahedron layer of SiO.sub.4 and an octahedron layer of MO.sub.6 (in which M stands for zinc or magnesium), which are bonded to each other, and it formed of a great number of such basic skeletons laminated in the direction of the C-axis. Many trials have been made to synthesize phylosilicates having a large specific surface area. For example, Japanese patent application Laid-Open Specification No. 10021/86 teaches that microcrystalline zinc phylosilicate or aluminum-containing zinc phylosilicate having an X-ray diffraction pattern of the fraipontite type and a specific surface area of at least 100 m.sup.2 /g can be obtained by reacting a water-soluble silicate, a water-soluble zinc salt and a water-soluble aluminum salt and/or a water-soluble aluminate at three-component oxide ratios of SiO.sub.2 of 5 to 45 mole%, ZnO of 35 to 65 mole% and Al.sub.2 O.sub.3 of 1 to 60 mole% in the presence of water.
According to this conventional technique, microcrystalline zinc phylosilicate or aluminum-containing zinc phylosilicate in which crystals are developed in the direction of the C-axis more finely than in natural fraipontite and the specific surface is about 200 m.sup.2 /g is obtained. However, from the viewpoint of increasing the property of adsorbing a dye or pigment, development of a phylosilicate having a larger specific surface area and a large pore volume is desired.
It is expected that if a mineral having the basic skeleton of the phylosilicate, in which lamination of the basic skeletons in the direction of the C-axis is prevented, is synthesized, it will become possible to obtain a synthetic mineral having a drastically increased specific surface area. However, according to the conventional techniques, it is still impossible to prevent lamination in the direction of the C-axis.